The evolution of long-lived species potentially involves systematic changes in cellular processes, including protein turnover and proteostasis. Whether or not long-lived species share common cellular strategies that contribute to their longevity and resistance to diseases of aging is not currently known. The long-term goal of this project is to characterize protein synthesis and breakdown, and cellular proliferation in short- and long- lived species to determine appropriate targets for slowed aging treatments. The overall objective of this project is to generate preliminary data characterizing protein turnover a a mechanism to maintain proteostasis in primary fibroblast cultures from short- and long-lived species in the presence and absence of an oxidative stress. The central hypothesis is that compared to short-lived species, cells from long-lived species: 1) have improved mechanisms of proteostasis as indicated by a greater ratio of protein synthesis to DNA synthesis compared to shorter-lived species, and 2) increase this ratio to a greater extent in response to a stress. This hypothesis is supported by in vivo work demonstrating increased protein synthesis relative to DNA synthesis in long-lived mouse models compared to their controls. The rationale for this research is that understanding mechanisms common among a variety of long-lived models, both within and between species, could provide key targets for slowing the aging process since shared characteristics are more likely translatable to humans. To generate the preliminary data for a future more comprehensive study, and for further hypothesis generation, the following specific aims are proposed: To measure proteostatic mechanisms in the absence or presence of an oxidative stress, and to measure protein synthesis rates of hundreds of individual proteins (kinetic proteomics) in the absence or presence of an oxidative stress. To accomplish these specific aims, novel methods using deuterium oxide will be used in primary fibroblasts cultured from rodent species with differing lifespan to determine protein synthesis, protein breakdown, cellular proliferation, and rates of synthesis of individual proteins. By using related species wit vastly different lifespans, the experiments will determine if the ability to maintain proteostasis through protein turnover is important for slowing the rate of aging. The proposed research is innovative because it systematically determines long-term synthesis and breakdown of proteins, cellular proliferation, and the synthesis rates of individual proteins in fibroblasts from short- ad long- lived species. The innovative techniques will allow the direct comparison of protein turnover rates to determine common strategies to maintain proteostasis in long-lived species. Completing the studies proposed should result in convincing preliminary data identifying a common cellular mechanism by which longer-lived species maintain proteostasis. Further, through novel kinetic proteomic analyses, candidate proteins related to minimizing protein damage will be identified. Finally, these findings will provide a foundation for evaluating additional species, other longevity models and age-related stresses, and tissue-specific cellular responses.